The muskrat is essentially a giant mouse that produces musk. Emitted by males, the musk is used to attract partners. The muskrat spends most of its time in water. If it needs to stay under water for a long period of time the muskrat can, like a beaver, drop its heart rate by half and reduce body temperature to burn less oxygen. The muskrat's stiff tail works as both a rudder and a propeller in the water, making them both speedy and well in control. They usually live in domed piles of cattails, reeds, grass, sticks, and mud. You can spot them in marshes, lakes, and swamps.